[libata ahci] tone down ATAPI errors

ATA devices don't generate many errors, so the preferred method is to
printk() when they occur.

ATAPI devices generate tons of exceptions during the normal course
of operation, so this change skips logging the most common class of
errors.

drivers/scsi/ahci.c

@@ -558,13 +558,15 @@ static void ahci_qc_prep(struct ata_queued_cmd *qc)
 	pp->cmd_slot[0].opts |= cpu_to_le32(n_elem << 16);
 }
 
-static void ahci_intr_error(struct ata_port *ap, u32 irq_stat)
+static void ahci_restart_port(struct ata_port *ap, u32 irq_stat)
 {
 	void __iomem *mmio = ap->host_set->mmio_base;
 	void __iomem *port_mmio = ahci_port_base(mmio, ap->port_no);
 	u32 tmp;
 	int work;
 
+	if ((ap->device[0].class != ATA_DEV_ATAPI) ||
+	    ((irq_stat & PORT_IRQ_TF_ERR) == 0))
 		printk(KERN_WARNING "ata%u: port reset, "
 		       "p_is %x is %x pis %x cmd %x tf %x ss %x se %x\n",
 			ap->id,
@@ -632,7 +634,7 @@ static void ahci_eng_timeout(struct ata_port *ap)
 		printk(KERN_ERR "ata%u: BUG: timeout without command\n",
 		       ap->id);
 	} else {
-		ahci_intr_error(ap, readl(port_mmio + PORT_IRQ_STAT));
+		ahci_restart_port(ap, readl(port_mmio + PORT_IRQ_STAT));
 
 		/* hack alert!  We cannot use the supplied completion
 	 	 * function from inside the ->eh_strategy_handler() thread.
@@ -677,7 +679,7 @@ static inline int ahci_host_intr(struct ata_port *ap, struct ata_queued_cmd *qc)
 			err_mask = AC_ERR_HOST_BUS;
 
 		/* command processing has stopped due to error; restart */
-		ahci_intr_error(ap, status);
+		ahci_restart_port(ap, status);
 
 		if (qc)
 			ata_qc_complete(qc, err_mask);